Such a conveying means is known from DE-OS 28 42 197. That publication shows a so-called clasping or adhesive plate serving as a releasable coupling member between the hook of a crane and an object to be moved. The latter has two protruding carrier pins which are engaged by pawls of the carrying plate. These pawls are moved by a wedge-like driving member between first and second limit positions. In one limit position the pawls release the carrier pins, while they engage behind the same in the other limit position, thereby locking the clasping plate to the object which is to be conveyed.
The wedge-like driving member in that case is moved back and forth by a remote controlled hydraulic cylinder. That is highly disadvantageous because hydraulic lines must pass from a remote control station all the way to the clasping plate and these hydraulic lines must cover the entire sweep of the hook of the crane. Of course, this is expensive and also very susceptible to disturbance. Furthermore, the objects to be gripped and moved must have carrier pins of special design, and those cannot be used for reasons of space alone in plants or with the structural elements inside the same if they are to be serviced by remote handling.
The subject matter of the invention relates more generally to remote handling techniques and, more specifically, to the special field of crane operation. Remote handling techniques are applied wherever the entrance of staff members is undesired, especially in nuclear and chemical plants.
The central member in crane operation is a crane, of course, and its rope and hook. The respective necessary tools, gripping members, or objects to be moved are suspended from the hook of the crane. Previously, in plants which had to be serviced by remote handling, the individual members were provided with lifting eyes to be engaged by the hook of the crane. The lifting eyes, of course, had to be mounted at the position of the center of gavity of the individual structural members of the system. This required a great number of points of attack because the position of the center of mass changes constantly when structural groups are disassembled into subgroups or are mounted in a system. Moreover, the points of attack may be covered by the subgroups. Lifting eyes were mounted on parts which were not covered. Covered parts, on the other hand, were provided at the position of the center of gravity with an internal thread into which an eye ring could be threaded by means of a manipulator, if required. However, it is a complicated handling step to thread annular screws or eyes into the exposed structural member by remote operation. Canting and damaging of the internal thread cannot be excluded. As a consequence, the threads must be re-cut which requires the structural groups to be removed into areas of higher handling quality.